yading@10: /* yading@10: * Common code between the AC-3 encoder and decoder yading@10: * Copyright (c) 2000, 2001, 2002 Fabrice Bellard yading@10: * yading@10: * This file is part of FFmpeg. yading@10: * yading@10: * FFmpeg is free software; you can redistribute it and/or yading@10: * modify it under the terms of the GNU Lesser General Public yading@10: * License as published by the Free Software Foundation; either yading@10: * version 2.1 of the License, or (at your option) any later version. yading@10: * yading@10: * FFmpeg is distributed in the hope that it will be useful, yading@10: * but WITHOUT ANY WARRANTY; without even the implied warranty of yading@10: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU yading@10: * Lesser General Public License for more details. yading@10: * yading@10: * You should have received a copy of the GNU Lesser General Public yading@10: * License along with FFmpeg; if not, write to the Free Software yading@10: * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA yading@10: */ yading@10: yading@10: /** yading@10: * @file yading@10: * Common code between the AC-3 encoder and decoder. yading@10: */ yading@10: yading@10: #ifndef AVCODEC_AC3_H yading@10: #define AVCODEC_AC3_H yading@10: yading@10: #define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */ yading@10: #define AC3_MAX_CHANNELS 7 /**< maximum number of channels, including coupling channel */ yading@10: #define CPL_CH 0 /**< coupling channel index */ yading@10: yading@10: #define AC3_MAX_COEFS 256 yading@10: #define AC3_BLOCK_SIZE 256 yading@10: #define AC3_MAX_BLOCKS 6 yading@10: #define AC3_FRAME_SIZE (AC3_MAX_BLOCKS * 256) yading@10: #define AC3_WINDOW_SIZE (AC3_BLOCK_SIZE * 2) yading@10: #define AC3_CRITICAL_BANDS 50 yading@10: #define AC3_MAX_CPL_BANDS 18 yading@10: yading@10: #include "libavutil/opt.h" yading@10: #include "avcodec.h" yading@10: #include "ac3tab.h" yading@10: yading@10: /* exponent encoding strategy */ yading@10: #define EXP_REUSE 0 yading@10: #define EXP_NEW 1 yading@10: yading@10: #define EXP_D15 1 yading@10: #define EXP_D25 2 yading@10: #define EXP_D45 3 yading@10: yading@10: /* pre-defined gain values */ yading@10: #define LEVEL_PLUS_3DB 1.4142135623730950 yading@10: #define LEVEL_PLUS_1POINT5DB 1.1892071150027209 yading@10: #define LEVEL_MINUS_1POINT5DB 0.8408964152537145 yading@10: #define LEVEL_MINUS_3DB 0.7071067811865476 yading@10: #define LEVEL_MINUS_4POINT5DB 0.5946035575013605 yading@10: #define LEVEL_MINUS_6DB 0.5000000000000000 yading@10: #define LEVEL_MINUS_9DB 0.3535533905932738 yading@10: #define LEVEL_ZERO 0.0000000000000000 yading@10: #define LEVEL_ONE 1.0000000000000000 yading@10: yading@10: /** Delta bit allocation strategy */ yading@10: typedef enum { yading@10: DBA_REUSE = 0, yading@10: DBA_NEW, yading@10: DBA_NONE, yading@10: DBA_RESERVED yading@10: } AC3DeltaStrategy; yading@10: yading@10: /** Channel mode (audio coding mode) */ yading@10: typedef enum { yading@10: AC3_CHMODE_DUALMONO = 0, yading@10: AC3_CHMODE_MONO, yading@10: AC3_CHMODE_STEREO, yading@10: AC3_CHMODE_3F, yading@10: AC3_CHMODE_2F1R, yading@10: AC3_CHMODE_3F1R, yading@10: AC3_CHMODE_2F2R, yading@10: AC3_CHMODE_3F2R yading@10: } AC3ChannelMode; yading@10: yading@10: typedef struct AC3BitAllocParameters { yading@10: int sr_code; yading@10: int sr_shift; yading@10: int slow_gain, slow_decay, fast_decay, db_per_bit, floor; yading@10: int cpl_fast_leak, cpl_slow_leak; yading@10: } AC3BitAllocParameters; yading@10: yading@10: /** yading@10: * @struct AC3HeaderInfo yading@10: * Coded AC-3 header values up to the lfeon element, plus derived values. yading@10: */ yading@10: typedef struct AC3HeaderInfo { yading@10: /** @name Coded elements yading@10: * @{ yading@10: */ yading@10: uint16_t sync_word; yading@10: uint16_t crc1; yading@10: uint8_t sr_code; yading@10: uint8_t bitstream_id; yading@10: uint8_t bitstream_mode; yading@10: uint8_t channel_mode; yading@10: uint8_t lfe_on; yading@10: uint8_t frame_type; yading@10: int substreamid; ///< substream identification yading@10: int center_mix_level; ///< Center mix level index yading@10: int surround_mix_level; ///< Surround mix level index yading@10: uint16_t channel_map; yading@10: int num_blocks; ///< number of audio blocks yading@10: /** @} */ yading@10: yading@10: /** @name Derived values yading@10: * @{ yading@10: */ yading@10: uint8_t sr_shift; yading@10: uint16_t sample_rate; yading@10: uint32_t bit_rate; yading@10: uint8_t channels; yading@10: uint16_t frame_size; yading@10: uint64_t channel_layout; yading@10: /** @} */ yading@10: } AC3HeaderInfo; yading@10: yading@10: typedef enum { yading@10: EAC3_FRAME_TYPE_INDEPENDENT = 0, yading@10: EAC3_FRAME_TYPE_DEPENDENT, yading@10: EAC3_FRAME_TYPE_AC3_CONVERT, yading@10: EAC3_FRAME_TYPE_RESERVED yading@10: } EAC3FrameType; yading@10: yading@10: void ff_ac3_common_init(void); yading@10: yading@10: /** yading@10: * Calculate the log power-spectral density of the input signal. yading@10: * This gives a rough estimate of signal power in the frequency domain by using yading@10: * the spectral envelope (exponents). The psd is also separately grouped yading@10: * into critical bands for use in the calculating the masking curve. yading@10: * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters yading@10: * determines the reference level. yading@10: * yading@10: * @param[in] exp frequency coefficient exponents yading@10: * @param[in] start starting bin location yading@10: * @param[in] end ending bin location yading@10: * @param[out] psd signal power for each frequency bin yading@10: * @param[out] band_psd signal power for each critical band yading@10: */ yading@10: void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, yading@10: int16_t *band_psd); yading@10: yading@10: /** yading@10: * Calculate the masking curve. yading@10: * First, the excitation is calculated using parameters in s and the signal yading@10: * power in each critical band. The excitation is compared with a predefined yading@10: * hearing threshold table to produce the masking curve. If delta bit yading@10: * allocation information is provided, it is used for adjusting the masking yading@10: * curve, usually to give a closer match to a better psychoacoustic model. yading@10: * yading@10: * @param[in] s adjustable bit allocation parameters yading@10: * @param[in] band_psd signal power for each critical band yading@10: * @param[in] start starting bin location yading@10: * @param[in] end ending bin location yading@10: * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) yading@10: * @param[in] is_lfe whether or not the channel being processed is the LFE yading@10: * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) yading@10: * @param[in] dba_nsegs number of delta segments yading@10: * @param[in] dba_offsets location offsets for each segment yading@10: * @param[in] dba_lengths length of each segment yading@10: * @param[in] dba_values delta bit allocation for each segment yading@10: * @param[out] mask calculated masking curve yading@10: * @return returns 0 for success, non-zero for error yading@10: */ yading@10: int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, yading@10: int start, int end, int fast_gain, int is_lfe, yading@10: int dba_mode, int dba_nsegs, uint8_t *dba_offsets, yading@10: uint8_t *dba_lengths, uint8_t *dba_values, yading@10: int16_t *mask); yading@10: yading@10: #endif /* AVCODEC_AC3_H */